Lubricating compositions and additives therefor



' .Thenresent invention Patented May I, 1951 R Q NG COMB T AND ADDITIVES William nn r Kingstoxr 11m, England, as-

, gl i s. (01.252-33) compri si nr vements in,-,or;, reiating to lubricat n composit seand additives therefor, I and relates more especially though not exclusively to lubricating compositions for use in internal, combustion ,enginesllm der conditions of. high, temperature to lubricate parts subject to, large ,mechanicalstresses.

In his previous British liiatent Specifications Nos. 398,222 and 423,441 the inventor has shown that lubricatin compositions formed by theaddition to alubricating oil of small amounts oio'rganic compounds of tinand of organic compounds of chromium respectively, results in tapmarked increasev in resistance to oxidation of the lubricant andreduces the formation of -gum and'pther deposits during use. -'I'he use of chromium oran organic compound; thereof in a lubricating oil together with one or more other substances such as an-organic compound of tin and/or lead has also beenproposedin British Patent specification No. 431,066. n According: tothe present invention a lubricats.composition;c mprises a. small: proportion of the organo -metallic, petroleum tsulphonate of. tin or chromium.

The inventor has found'that such lubricating compositions have particularly good-resistance to oxidation under conditions of use in andnterna-l combustion engine and hav also good anti-corrosive properties, and do not'formexcessive deposits in thepiston ring grooves or promote lacquering of the pistons.

"'Iheiresistance to physical wear, oxidation or other-corrosion of metallic tin and chromium when applied as a coating to pistonsandtcylinders respectively ofinternal combustion engines has, subsequently 'to the proposals of the said prior specifications, become well known and es= tablished and the subjectoflaccepted use in engines, 0fl; high,,quality; f I'he inyentor has also foundthat some analogous resistance to corrosive or abrasive wear of piston and, cylinder surfaces may be obtained in an-internal combustion engine by the,use of tin and/or chromium ;,petro leum sulphonates in the lubricant for ,the engine.

r n 1 the. pr s n v ntion p vid a so a -1 br oa e c mosit on.c r n bricating oil base in which i incorporated a minor-:nr portion inorganic c mp u d of bot chromiumoand tinwhereof at least one-of. such organic compoundsis a petroleum sulphonate.

.oCp-lenveniently such a lubricating composition comprises aminorproportionzof-chromium or tin petroleum sulphonateanda furthenorganic com.

pound other than a petroleum tsulphonateof ,tin or chromiumrespec'tively.

i It is to be understoodalsoas.within thepresent invention to employ. in a lubricating v.oil base chromiumand tin petroleum sulphonates, iniadmixture and/or other organic compounds of chromium andwtin in admixture. It istosbe understood iur'ther that all compounds of chromium-and tin the use-.ofwhich iscontemplated by the present invention are thosewhich are solublein the lubr icatingtoil base. --Examples-of the'organio compounds of chromium and tin -(other than the ipetroleumtsulphonatest referred to above are conveniently afforded by theoleates, naphthenates or substiltutd phenola'tes', and such compoundsand' the sulphonates referred to above may .each be employed in any desirable proportion for example, to an extent of from- 005% to 2.0%,by'weight in the-composition;

According to one example of theinvention a lubricating composition-suitabl sfor use'in a con.- ventional petrol engine is afforded by a lubricating oil basedn-Whichthere is incorporated 0,1 by-wei-glit of; chromium and/or tin petroleum 'sulphonate' together with-0.4% by weight of other organic ---tiii-and/orchromium compound respectively; Inother examples a similararela 'beemployed;

=;-(;onveniently a #lubricating composition provided in accordance with the invention comprises also a small proportion of alkali (e'. 'g. sodium) petroleumsulphonate and/oralkalineearth (e. g.

'tiveproportion'by weight of such compounds may calcium) -petroleum sulphonate Conveniently also-the alkaliland/or alkaline earth petroleum sulph onate's "are selectively included in the =omposition to exclude such compounds of a pro-- -nouncedacorros'ivenature: Apart from benefits found in nor'mal running of an engine withiu'se of the lubricating compositions no proposed, .the inclusion intthe latt'er o f the-saidsodium and calcium petroleum sulphonate s, particularly in their selectively refined form,-haveibeen found to aiford :pr'ote'ction to the 'c ylinders and other parts of the engine subject to corrosion during periods of storage of the engine or when the latter is otherwise stationary.

The-lubricating composition may comprise a proportionof from :0.01%' to 2.0 by weight of added pe'trol'eum sulphonate and preferably contains ,about 11.0% 1 shy weight' -of .theiorganometallicm petroleum .esulphonate'" of chromium and/drwtini with v a vproportion of selectively in:- cludedealkali tori alkaline .eartli petroleum l ulimprovers, pour-point depressants, or materials for increasing the film rupture strength of the Composition and/or other anti-oxidant and/or detergent additives may also be added to the lubricating composition provided by the invention. Thus a small proportion of tri-ortho-cresyl phosphate or of tributyl phosphite may be employed in a lubricating oil in conjunction with the tin and/or chromium petroleum sulphonate in order also to enhance the film rupture strength and other properties of the composition.

The present invention also includes a process of p'roducing an additive material for incorporation in a lubricating composition as referred to above from petroleum sulphonic acids, for example,by reacting the alkali or alkaline earth petroleum sulphonates with appropriate salts of chromium and/or tin. The latters salts may be chrome alum or chromium sulphate or chromium chloride, or other suitable inorganic salts of chromium, or amixture of suitable chromium salts, and/or stannous chloride or other suitable inorganic salt or salts of tin, and the chromium and tin salts may also be employed in admixture in proportions to yield under the reaction conditions chromium and tin petroleum sulphonates in a desired relative proportion by weight. Conveniently, the reaction components and/or conditions are adjusted to produce a desired proportion of unreacted alkali (e. g. sodium) or alkaline earth (e. g. calcium) petroleum sulphonate in the reaction product. The amount of the sodium or calcium petroleum sulphonate in the final lubricating oil composition may range from 0.1% to 1.0% by weight. .The reaction may be carried out in aqueous and/or alcoholic solution, and

in the latter case according to one specific method stannous chloride and/or chrome alum are added to an alcoholic solution of calcium petroleum sulphonate in equivalent molecular proportions. The mixture is vigorously agitated and the resultant precipitated calcium sulphate for example, filtered oif and the alcohol evaporated.

The invention includes also a lubricant additive material for use in the production of a lubricating composition as referred to above comprising the product of a reaction as described in theimmediately preceding paragraph. The tin or chromium petroleum sulphonates or mixtures thereof so obtained may be viscous liquids or solids according to the nature of the petroleum sulphonates or sulphonic acids originally employed. The compounds produced in this way are also oil soluble and filter passing when in oil solution, the liquid compounds, however, being more readily soluble. l

It will be appreciated that the original sulphonic acids, from which the chromium or tin compounds are now to be derived, are the oil soluble, so-called mahogany acids. Separated oil soluble sulphonic acids are commercially available in products of the sulphonation of mineral oil of a paraffinic or naphthenic nature and more usually after neutralisation of the'free acids by caustic soda or lime to produce either sodium or calcium petroleum sulphonates in admixture with mineral oil. Such a commercially available material, for example, has been found to contain some 50 to 55% of sodium petroleum sulphonate.

Example 1 In one example of the invention 500 grams of the latter commercially available material was mixed with 150 grams of chrome alum and the mixture heated with 2.5 litres of water at a temperature of 100 C. for 18 hours. After subsequent evaporation of the water the residue was then twice extracted with 2.5 litres of benzene maintained at its boiling point for 1 hour. After filtration through a streamline filter the benzene solution gave the following analysis:

Per cent by weight Total'sulphonates and. oil 6.0 Chromium 0.07

These figures correspond to a conversion of approximately 25% of the sodium petroleum sulphonate to the corresponding chromium compound. The probable composition of the material after evaporation of the benzene is:

Per cent by weight Chromium petroleum sulphonate to Sodium petroleum sulphonate about 40 Lubricating oil to Example 2 In a further example of the invention giving a higher yield of chromium petroleum sulphonate, 250 grams of sodium petroleum sulphonate was mixed with 40 grams of chromic chloride and 2 litres' of industrial alcohol and heated under refiux conditions for 6 hours. The alcohol was then boiled off and 2 litres of benzene added. The mixture was then boiled for 2 hours and after cooling the resulting solution was filtered through a stream line filter. The benzene was then boiled off and the resulting compound has the composition on an oil free basis of Per cent by weight Chromium petroleum sulphonate 71 Unreacted sodium petroleum sulphonate"--- 29 Example 3 Example 4 In another example of the invention 600 grams of the commercial sodium petroleum sulphonate referred to above was mixed with grams of stannous chloride and heated in the presence of 1800 cc. of industrial alcohol for a period of nine hours in a water bath with the use of a reflux condenser. After subsequent removal of the alcohol by distillation the residue was then twice heated in succession with 300 cos. of benzene for 1 hour. After passage throug a streamline filter the benezene solution was found to include:

I Per cent by weight Total sulphonates and oil 0 estate;

Per cent byweight Tin petroleum sulphonate ;l 45 Sodium petroleum sulphonate 10-15 Lubricating oil 4045 It will be noted that in the four examples given abovethe desired material'r'nay be' obtained as a clear solution in" benzene and may be. used as such. I

By way of examples or" processes for the production of tin and chromium petroleumsulphonates giving high yields of the latter materials with very little or "no unreacted alkali petroleum sulphonate in thefinal product, the following two further examples are given. In both these examples a commercially available sodium petroleum sulphonate material was employed having an approximate content by weight of- 38% sodium petroleum sulphonate 52% oil 10% water, alcohol and sodium sulphate Example 5 f 4 lbs. of the sodium petroleum sulphonate material were added to about 3 gallons of water and stirred well while heating to 90? C. to produce a fluid milkysolution. 4, lb. oftin chloride '(SHClZZHZO). was dissolved in 560 cos. of cold water and-added to the heated milky sodium petroleum sulphonate solution, stirring being continued. An oil concentrate of tin, petroleum sulphonate was precipitated and settled at the bottom of the reaction vessel.

After cooling the water layer was easily decanted or siphoned off from the very viscous precipitate which was washed by addingl gallon of water and heating to the boiling point while again stirring well. 4 lbs. of mineral oil'were now stirred in to produce a concentrate which I of "Tlbs': 6 /9, ozs. was'obtained' having anapproximate composition of Example 6 p 4 lbs. of'the sodium petroleum sulphonate material were added to aboutj'4 gallons of water and mixed-"while heatingto 90 C. 'A-hot solution atQDiC. of 13 oz. of chrome alumin gallon of water was then added while stirring and the mixture allowed-to'stand'overnight. Wate r was their decanted from'the viscous oil solutionwhich had settledin the reaction vesselandgwhich was 'lwashed'with a further 2 gallons of water byheatsw' 'i insrem ndstirr ?Wal s; ile'f s ihg thewater wa's again decantedand theremfaining product finally dried by' heating' to 250 F. in a current of air. Centrifuging was considered unnecessary in view of the appearance of the product but maybe desirable under certain circumstances.

-The product represented an 87% yield of 3 lbs. 2 ozs. having an approximate composition of- I n Per Cent Chromium petroleum sulphonate l -31.5 Sodium p'et'roleum'sulphonate 6 to 8 Mineral oil. 60.5 to 62.5

Analysis of the product gave the results:

Per Cent Chromium 1.31 Sodium 0.47 Ash 3.79

If desired, chromium and tin petroleum sulphonates may be prepared in admixture by the simultaneous reaction of chrome alum, chromium sulphate, or chromium chloride, or any other suitable inorganic salt of chromium, or any preferred mixture of such salts, and stanneus chloride, or other suitable inorganic salt or salts of tin with the: first mentioned commercial sodium petroleum sulphonate or an equivalent materiaL. the proportions of chrome alum and/or said other chromium salt or salts and stannous chloride or other preferred salt or salts employed together for this reaction preferably being such as tosecure a desired content of chromium and tin'petroleum sulphonates in relation to one another in the reaction product. A similar proceduremay also be adopted, if desired, in the preparation of mixed chromium and tin petroleum sulphonates free from, alkali or alkaline earth sulphonates by production from the free petroleum sulphonic acids. The latter may be obtained, for example, by the actionof hydrochloric acid on the sodium or calcium sulphonates. The

chromiumand tin compounds may also be separately produced in this way free from sodium or calcium sulphonates. Such processes with the use offree sulphonic acids however, are more costly and troublesome than those described above in which the stable unreacted sodium and/or calcium sulphonate are also present in the reaction product. By variation ofthe latter process, for example as regards the temperature or duration, at or for which the reaction iseffected or by the choice of starting materials, a desired content of such sodium and/or calcium sulphonate in the reaction product may also'be secured, and it may sometimes be advantageous to efiect a reduction in the quantity of the sodium sulphonate produced with the corresponding chromium compound as in the second specific example referred to above, without proceeding to a substantially complete conversion of the sodium petroleum sulphonateas described in Examples 5 and 6.

Proportions-of from'0.05% up to 2.0% 'by weight of the chromium and/or tin compounds arefound to be advantageously employed in a lubricating composition, and in a particular mixture 0.1% of the chromium compound and 0.4% of the tin compound is found to be especially desirable either when used alone or with less. than an equal quantity of the .unreacted sodium and/or calcium petroleum sulphonate.

0f the known agents which may also be added to lubricating compositions (e. g. for imparting anti-oxidantor detergent properties and/or for increasing the film ruptur'strength) it has been 'found particiflarlysatisfactory to include also an aromatic hydroxy-substituted thioether and/or (11- or poly-sulphide compound as described in British Specifications Nos. 455,235 and 561,898 and/or a phosphite or thiophosphite ester thereof as described in British Specification No. 574,445. Alternatively or in addition tri-cresyl phosphate may also be included in the composition. Such compounds may be employed in the composition to an extent of about 0.1% to 1.0% by weight.

Again the additives proposed by the present invention may also be employed, for example, and with advantage to replace a metal soap where the latter has been included in a lubricating composition. The organic compound of tin employed in the "compositions proposed in the inventors prior British Patent Specification No. 548,390 may thus be replaced by the tin and/or chromium petroleum sulphonates now proposed, while the latter may also be employed in place of the metal soap in the compositions described in the inventors prior British Patent Specification No. 510,244.

Lubricating compositionsprovided by the invention have increased resistance to oxidation and sludge formation at all temperatures and also show a reduced tendency for the production in use of gummy deposits by thermal decomposition. The compositions also have improved detergent properties.

The resistance to corrosive or abrasive wear of cylinder and piston surfaces, as well as bearing surfaces referred to as analogous to that secured by the application of a metallic coating of chromium and tin respectively, is also secured to a remarkable extent. It is also found that although commercial calcium and sodium petroleum sulphonates separately usedin a lubricating oil produce markedly increased corrosion, sodium and calcium petroleum sulphonates are capable of use with chromium and/or tin petroleum sulphonates without a marked increased of corrosion and with improved properties of oxidation resistance and detergency imparted to the lubricant.

The surprising absence of increased corrosion under the latter conditions is particularly true in the case of the presence of sodium or calcium petroleum sulphonate as an unreacted residue in the preparation of the chromium and/or tin compounds. This result is apparently due to a selective reaction of the chromium and/or tin salts with the less stable and more corrosive sodium or calcium sulphonate molecules so that the residual alkali or alkaline earth sulphonate molecules in the reaction product are of a more desirable, more stable and less corrosive nature. It is accordingly preferred to include in the lubricating compositions an alkali and/or alkaline earth petroleum sulphonate of this nature which may be derived in the manner indicated.

Comparative laboratory test results were secured in:

(A) The standard Air Ministry oxidation test,

(B) A corrosion test in which lead or mild steel test pieces were rotated at 700 R. P. M. in contact with the oil and only partly immersed during heating of the oil to 180 C. for 12 hours, loss in weight of the test pieces being recorded and polished copper being present in the oil to act as catalyst.

(C) A filtration test in which an oil sample .was passed through a closely packed and highly efficient filter of the streamline type, the tin tive material.

bearings. weight of bearing parts of 28 mil1i'grams as com and/or chromium content of the oil sample being determined before and after filtration.

The tests were conducted on three oil samples as follows:

(1) A solvent refined lubricating oil without additives viscosity 489 Redwood No. 1 at F. centistokes) and viscosity index of 93.

The lubricating oil of sample 1 to which 0.4% by weight of the commercial sodium petroleum sulphonate first referred to above had been added.

The lubricating oil of sample 1 containing 0.1% by weight of chromium petroleum sulphonate, 0.4% by weight of tin petroleum sulphonate and 0.35 to. 0.4% by weight of sodium petroleum sulphonate left as unreacted residue in the production of the chromium and 7 tin compounds.

Test results secured were as follows:

Oil Sample l 2 3 Viscosity at 100 F.:

Redwood N o. 1 (Secs) 487 491 492 Oentistokes 120 121 121 Carbon Residue, per cent wt 0. 2 0. 38 0. 3 (A) Oxidation Test:

Viscosity after Oxidation (Cs) 216 175 206 Viscosity Ratio 1.8 1.45 1. 7 l. 7 l. 28 1. 9 Carbon Residue increase l. 5 0. 9 l. 6 (B) Corrosion Test:

Weight loss (mg.)

ead about 500 5.0 Steel above 30.0 0. 8 (C) Filter Test:

Tin before filtration per cent.- 0. 005 Tin after filtration ..clo 0. 004 Per cent less Nil Chromium before filtratiouper cent 0. 003 Chromium after filtration do 0. 003 Per cent less 1 Nil The lubricating composition provided by the invention includes additives of a highly oil soluble nature capable in solution in oil in the desired proportions of passing a stream line filter without the effective removal of any of the addi- Since the latter act as wetting agents they also confer benefit particularly in use in internal combustion engines in securing the spread and retention of an oil film on cylinder and other rubbing surfaces especially when such engines are left stationary after running. This is particularly so in the case of lubricating compositions provided by this invention containing sodium petroleum sulphonate and/or calcium petroleum sulphonate in the mixture, in that at ordinary temperatures e. g. during storage of the engine, the last-mentioned sulphonates act as'rust preventers and generally as corrosion inhibitors,

, Lubricating compositions provided in accordance with the present invention had also been subject to practical tests under operating conditions in a conventional type of single cylinder test engine. One such test was conducted with a lubricating composition in which there was incorporated 1.2% by weight of tin petroleum sulphonate as produced in Example 4 (and thus including a proportion of unreacted sodium petroleum sulphonate) and 0.3% of chromium petroleum sulphonate as produced in Example 3 (and thus including a proportion of unreacted calcium petroleum sulphonate). After the test run the engine was found to have a very clean piston and no varnish or lacquer deposit on the Bearing corrosion showed a loss in pared with a loss of 153 milligrams for a similar test run with the unmodified lubricating oil in which the tin and chromium petroleum sulphon-ates were incorporated.

Other satisfactory engine test results have been obtained with the use in a lubricating oil of tin and/or chromium petroleum sulphonate in conjunction with other organic compounds of chromium and/or tin respectively, confirming the benefits indicated above. Other known organic compounds, such'as mercaptobenzothiazole, have also been included with advantage in such compositions. Good results have thus been obtained with the use in a lubricating composition of from 0.1% to 0.2% of tin petroleum sulphonate and 0.4% to 0.8% of chromium oleate and, alternatively, with theuse of from 0.1% to 0.2% of chromium petroleum sulphonate with 0.4% to 0.8% of tin oleate. A number of laboratory and engine tests have been made also to confirm the advantages secured in particular with the use of tin petroleum sulphonate in conjunction with a suitable organic chromium compound, for example in proportions corresponding to those suggested for tin petroleum sulphonate and chromium oleate.

I claim:

1. A lubricating composition, which comprises, a mineral lubricating oil base in which is incorporated between 0.05% and 2% by weight of tin petroleum sulphonate and between 0.05% and 2% by weight of chromium petroleum sulphonate.

10 2. A composition in accordance with claim 1 in which the amount of chromium petroleum sulphonate is between 0.1 and 0.3% and the amount of tin petroleum sulphonate is between 0.4% and 1.2%.

3. A composition in accordance with claim 1 which also contains between 0.1% and 1.0% of a sulphonate selected from the group consisting of sodium petroleum sulphonate and calcium petroleum sulphonate.

4. A composition in accordance with claim 1 which, also contains between 0.35% and 0.4% sodium petroleum sulphonate.

WILLIAM HELMORE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A LUBRICATING COMPOSITION, WHICH COMPRISES, A MINERAL LUBRICATING OIL BASE IN WHICH IS INCORPORATED BETWEEN 0.05% AND 2% BY WEIGHT OF TIN PETROLEUM SULPHONATE AND BETWEEN 0.05% AND 2% BY WEIGHT OF CHROMIUM PETROLEUM SULPHONATE. 